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Chinese Journal of Biological Control ›› 2022, Vol. 38 ›› Issue (5): 1083-1093.DOI: 10.16409/j.cnki.2095-039x.2022.09.004


Silencing of Chitin Synthase 1(HvCHS1) by Dietary RNAi Inhibits the Survival and Development of the 28-Spotted Potato Ladybird,Henosepilachna vigintioctopunctata

LUO Xuming1, CHEN Shimin1, PAN Guang2, YANG Chunxiao3, PAN Huipeng1   

  1. 1. College of Plant Protection, South China Agricultural University/Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, Guangzhou 510642, China;
    2. National Modern Agricultural Industry Science and Technology Innovation Center of Guangzhou, Guangzhou 510520, China;
    3. South China Agricultural University, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou 510642, China
  • Received:2022-07-15 Published:2022-10-20

Abstract: The growth and development of insects are affected by the balance between the synthesis and degradation of chitin,and chitin synthase 1(CHS1) is one of the key enzymes involved in insect chitin synthesis.This study aims to investigate the effects of CHS1 on survival and development of Henosepilachna vigintioctopunctata using dietary RNAi.HvCHS1 sequence obtained from the genome data of H. vigintioctopunctata was analyzed for physicochemical properties and homology with other insects through bioinformatics methods.The temporal and spatial expression patterns of HvCHS1 were analyzed by RT-qPCR.The RNAi (RNA interference) of HvCHS1 was carried out by ingestion of in vitro synthesized and bacterially expressed dsRNAs.The mortality and pupation rate of H. vigintioctopunctata were recorded,and the epidermal changes were observed by the hematoxylin and eosin (H&E) staining.The open reading frame of HvCHS1 is 4680 bp,encoding 1559 amino acid with a relative molecular mass of 177.5 kDa.The expression levels of HvCHS1 were greater in cuticle than in other tissues.In addition,ingestion of dsHvCHS1 led to a significant decrease in the survival rate and pupation rate of H.vigintioctopunctata with a significant dose-dependent effect.The mortality rates of 1st instar larvae were 42.00%,82.00% and 94.00% when the larvae were fed with 50 ng/µL,250 ng/µL and 500 ng/µL dsHvCHS1,respectively.The pupation rates of 4th instar larvae fed with 50 ng/µL,100 ng/µL and 200 ng/µL dsHvCHS1 were 17.04%,34.07% and 68.52%,respectively.Moreover,ingestion of bacterially expressed dsHvCHS1 resulted in high larval mortality of 64% and 60% in the 1st and 3rd instar larvae,respectively,whereas it had no impact on the survival rate of adults.Finally,H&E staining assays revealed the ingestion of dsHvCHS1 prevented new abdominal cuticle formation.It is obvious that HvCHS1 is responsible for the new cuticle formation during larvae ecdysis,and it is a potential RNAi target gene for the bio-control of H.vigintioctopunctata.

Key words: Henosepilachna vigintioctopunctata, chitin synthase 1, dietary RNAi, mortality, pupation rate

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